The snapshot feature in any virtualization software is powerful because it allows you to "snap back" (revert) and "snap forward" in time. With this, you can perform installations and revert if they don't work. You can make configuration changes over and over again until you get them right. And, you can go back to a point in the "life" of that virtual machine when it was freshly installed and brand new.
Sure, snapshots are cool but they can also be dangerous. These snapshots can take up a ton of disk space and, potentially, cause you to run out of space in your ESX Server datastores. By running out of space, you could, potentially, experience downtime and end users could be upset when their virtual desktops or applications no longer work.
Finding which virtual machines have snapshots, how old those snapshots are, and how much space they take up can be very time consuming in the vSphere client graphical interface. You have to click on each virtual machine, look to see if the Revert to Snapshot button is colored and, if it is, go into the snapshot manager and look at each snapshot.
Fortunately, vExpert and Microsoft MVP Hal Rottenberg's PowerCLI videos - the new Train Signal vSphere Pro Vol 1 training course - show you how to find old snapshots in your vSphere infrastructure, report on how old they are, and how much space they take up in your datastores. By finding these snapshots early, before they cause trouble, you can delete unneeded snapshots to save space and prevent downtime.
Hal makes learning PowerCLI and PowerShell fun and easy. Honestly, I before I watched this video, I had only used one PowerShell script. After Hal's excellent teaching on how it works, I am excited about PowerShell and feel like I could write just about any script!
Here's a sample from Hal's PowerCLI training video...
For more information on what else Hal covers and what else the entire vSphere Pro Vol 1 video covers, visit Train Signal vSphere Pro Vol 1 course outline.